How to Speed up code

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elisa ewin
elisa ewin 2016-5-16
编辑： Jan 2016-5-16
Hi, I have this code: I have a number of user and for all of them I want to find the id of locations that they have visited, the stay time and, combining this elements,the semantic trajectories associated to them
for userid=1:usercount
% identification locationId: the location id are in a struct s.loc_ids
for i=1:size(Trajectories(1,userid).label,1)
Trajectories(1,userid).locationId(i,1)=s(1,k).loc_ids(i,1);
end
for i=1:size(Trajectories(1,userid).label,1)-1
% stayTime (difference between time of arrival and time of exit from a cell) for every user
Trajectories(1,userid).stayTime(i,:)=abs((Trajectories(1,userid).dateAll(i+1,:)-Trajectories(1,userid).dateAll(i,:)));
% stayLocation for every user
Trajectories(1,userid).stayLocation(i,:)=[Trajectories(1,userid).locationId(i,1) Trajectories(1,userid).dateAll(i+1,:) Trajectories(1,userid).stayTime(i,:)];
% semantic trajectories for every user
Trajectories(1,userid).semanticTraj(i,:)=[Trajectories(1,userid).stayLocation(i,:) Trajectories(1,userid).label(i,:)];
end
end
It run and do what I want but It's slow: can you help me to obtain better performance?

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采纳的回答

Jan
Jan 2016-5-16
编辑：Jan 2016-5-16
for userid = 1:usercount
T = Trajectories(1, userid); % Nicer code...
n = size(T.label,1);
T.locationId(1:n) = s(1,k).loc_ids(1:n);
% Or perhaps:
% T.locationId = s(1,k).loc_ids;
T.stayTime = abs(diff(T.dateAll - T.dateAll, 1, 1));
T.stayLocation = [T.locationId(1:n-1), T.dateAll(2:n, :), T.stayTime(1:n-1, :)];
T.semanticTraj = [T.stayLocation(1:n-1,:), T.label(1:n-1, :)];
Trajectories(1, userid) = T;
end
Without your data, I cannot debug this. Perhaps you need some .' operators for transposing.

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